Ok folks I have search countless threads to no avail. I have a pioneer avic x850bt with the infamous metra kit. it has been installed now for a few months.however as time has gone on i have developed a very annoying whistle/buzz in just the passenger side tweeter and door speaker that climbs with the rpms and gets louder when you turn the headlights on and other electronics in the car. for a while if i messed with the havac fan switch it would stop but now that doesn't work and the noise is more or less constant in just the two mention speakers. i have removed the headunit and checked connections etc. what am i missing here? am I alone on this one? Thanks all for listening and I hope someone has some ideas?

 

Ground loop noise, its always recommended when upgrading to an aftermarket unit to run an independent ground to a chassis point.

 

Meaning instead of running the ground from the head unit into the harness, run it to a flat metal surface somewhere on the car.